Lustrum (noun) (literary)
A period of five years.
Late 16th century: from Latin, originally denoting a purificatory sacrifice after a quinquennial census.
“She’s been my friend for eight lustrums now and forty years is a long time!”
Nothingburger (noun) (Chiefly US)
A person or thing of no importance, value, or substance. Now esp.: something which, contrary to expectations, turns out to be insignificant or unremarkable.
1950s: from nothing and burger. Added to the OED October 2018.